Docs: Update 6.3.1 plugin download link

Author: spinscale

README.md

@@ -6,6 +6,7 @@ Uses the [langdetect](https://github.com/YouCruit/language-detection/) plugin to
 
 | ES    | Command |
 | ----- | ------- |
+| 6.3.1 | `bin/elasticsearch-plugin install https://github.com/spinscale/elasticsearch-ingest-langdetect/releases/download/6.3.1.1/ingest-langdetect-6.3.1.1.zip` |
 | 6.3.0 | `bin/elasticsearch-plugin install https://github.com/spinscale/elasticsearch-ingest-langdetect/releases/download/6.3.0.1/ingest-langdetect-6.3.0.1.zip` |
 | 6.2.4 | `bin/elasticsearch-plugin install https://github.com/spinscale/elasticsearch-ingest-langdetect/releases/download/6.2.4.1/ingest-langdetect-6.2.4.1.zip` |
 | 6.2.3 | `bin/elasticsearch-plugin install https://github.com/spinscale/elasticsearch-ingest-langdetect/releases/download/6.2.3.1/ingest-langdetect-6.2.3.1.zip` |